POTASSIUM AND SODIUM APPLICATION EFFECTS ON SOIL-TEST VALUES, AND TURFGRASS QUALITY,CLIPPING YIELD AND ELEMENTAL COMPOSITION OF BERMUDAGRASS GROWN IN A SAND SOIL

摘要

Frequent applications of potassium chloride (KCl) and sodium chloride (NaCl) were used to establish a broad range of soil potassium (K) and sodium (Na) concentrations in a sand soil with established Tifway bermudagrass (Cynodon dactylon (L.) Pers.X C.Transvaalensis Burtt-Davy) maintained as a fairway.Despite the range of soil K and Na,few and inconsistent agronomic effects were observed over a four year period.Reduced visual bermudagrass quality commonly was observed in plots that received no K fertilization,but there were few noteable responses at K fertilization rates exceeding 1.25 g K m-2 month-1,even though N was applied at 10 g m-2 month-1 which produced a wide range of N:K fertilization ratios.Potassium fertilization rarely increased bermudagrass clipping yield,although in the absence of K fertilization soil-test and plant tissue K generally were below established minimum levels.Sodium applications reduced bermudagrass quality ratings on some dates,particularly near the end of the study,but the effect was sporadic and inconsistent.Likewise,Na applications had few and inconsistent effects of clipping yield.Potassium fertilization increased tissue K relative to the no K treatment,but there was little increase in bermudagrass tissue K for application rates greater than 1.25 g K m-2 month-1.Tissue Na was increased by Na applications,but it was low relative to tissue K.Interestingly,tissue Na was greater in the absence of K and Na applications than in the presence of any rate of K and Na applied,and even the lowest rate of K fertilization substantially reduced tissue Na.Soil pH was somewhat increased by Na applications,which was also associated with reduced soil and tissue calcium and magnesium.The results do not suggest that additional K fertilization is beneficial for bermudagrass quality or clipping yield when elevated soil Na is encountered.